Mode of action of thiocyanate and iodide in relation to IAA metabolism |
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| Authors: | NORMAN H STEPHEN GORDON T COOK HENRY J DUNCAN |
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| Institution: | Agricultural Chemistry, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, Scotland |
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| Abstract: | Whole plant studies have reaffirmed that of the halides and pseudohalide thiocyanate, only iodide and thiocyanate possess defoliant properties. Established work has indicated their possible involvement with IAA (indole-3-acetic acid). In vitro studies have suggested that IAA destruction is not through a direct interaction between IAA and the halides and pseudohalide but depends on their conversion to the halogen or pseudohalogen which can then destroy IAA. This may be accomplished by the peroxidase enzyme system for iodide only and docs not provide a mechanism for thiocyanate activity. However, both iodide and thiocyanate have chemical oxidation potentials suitable for their conversion to the halogen or pseudohalogen respectively via the photosynthetic apparatus. Hence, this would provide an explanation for then activity and the apparent inactivity of bromide, chloride and Buoride which would be oxidized very slowly or not at all. |
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